The present invention relates to a technique of data recording on a recordable optical disk.
The optical disk is able to store a large amount of information and has a feature of compatibility.
Of all kinds of optical disks, DVD (Digital Versatile Disk) that can store a large amount of information for computer, video images and music on the same recording medium has attracted our attention as a new large-capacity recording medium for PC and AV. The popularization of playback-only DVD player and the appearance of DVD recorders that can also record DVD are rapidly expanding the DVD market.
As the recordable optical disk becomes widely used, the user has treated the optical disk compatibility as important. However, since most of widespread DVD players do not support DVD-RAM (DVD-Random Access Memory) and DVD-RW(DVD-ReWritable) as the rewritable formats that some DVD recorders employ; they have no compatibility and thus cannot reproduce the rewritable DVD-RAM optical disks and so on. Therefore, when setting the DVD-R (DVD-Recordable) standard that complies with the DVD-video format, we will see a current movement to support the DVD-R media which are recordable optical disks to assure high compatibility.
During the real-time recording of data on a disk by a recorder, we sometimes switches off the power supply to the recorder or takes the disk out of the recorder when arbitrary data has been recorded before data is completely recorded on the entire surface of the disk. At this time, in order to assure to additionally record new data continuously to the already recorded data, it is necessary to manage the data recorded up to that time on the disk. Therefore, management information (hereafter, called intermediate IFO file) to manage this disk is updated each time data is recorded.
FIG. 1 shows the updating of intermediate IFO file on a DVD-R when data of video scene is recorded in a form of file. The disk-recording region is generally divided into a region for recording user data (video information region 1) and a management information region 2 for managing files of data recorded on the disk according to the kind of disk. FIG. 1(a) shows a positional relation between the intermediate IFO file and each video-scene file on a DVD-R when video-scene 2 has been recorded. The file 4 of video-scene 2 is additionally recorded continuous to the file 3 of video-scene 1. In addition, since the file 4 of video-scene 2 is added to change the file structure on the disk, the intermediate IFO file 2 (as indicated by reference numeral 5) is recorded in turn to update the management information.
Since the DVD-R is a write-once medium, a new intermediate IFO file cannot be recorded on the old intermediate IFO file, or overwritten thereon. Thus, when the management information is updated, a new intermediate IFO file is recorded in turn continuous to the previously recorded one as in the video information region 1. Accordingly, the finally added intermediate IFO file indicates the latest file structure on the disk.
FIG. 1(b) shows the state that files of video scene have further been recorded from the state of FIG. 1(a) up to the file 6 of video scene N where there is no recording space, or no video scene can no longer be recorded. At this time, the file structure on the DVD-R is concluded, and the information for managing that state is indicated by the intermediate IFO file N (represented by numeral 7). Thus, by reproducing the intermediate IFO file N (represented by 7), it is possible to access to all video-scene files.
However, the DVD player cannot reproduce the video scene files in this state of FIG. 1(b). This is ascribed to the characteristics of the DVD player that is designed to assume the reproduction of DVD-ROM disks produced by prepress. The DVD-ROM format describes that video information and so on are recorded in spiral from the inner to outer periphery. In order for the DVD player to reproduce both types of format even when data is recorded on the DVD-R disk, it is necessary to continuously record from the inner periphery without including non-recorded portions as in the DVD-ROM format disk.
In order that the user can completely record data (files) on a disk and reproduce the disk on DVD player with good compatibility to both formats, it is necessary to finalize that disk. When the disk is finalized, the finally updated intermediate IFO file N (represented by 7) is newly added in a format based on the DVD-ROM format as final management information (hereafter, called final IFO file 8), as shown in FIG. 1 at (c). The DVD player reproduces this final IFO file 8, thus acquiring the file structure on the disk so that it can access to each video data. The non-recorded portions are filled with dummy data 9 so that the recording space can be continuously occupied by some data. Under this condition the DVD player can reproduce the DVD-R disk.
When IFO files and video scene files are recorded in turn, junctions called linking are produced between these files. This linking will be further described with reference to FIG. 2. FIG. 2 shows examples of a disk 80 μm eccentric.
FIG. 2(a) schematically shows a linking portion formed on the disk when a video scene file is additionally recorded. The closing end of recorded data 10 at the previous ((N−1)th) location is connected to the beginning end of recorded data 12 at the (Nth) location of video data by a linking portion 13 as shown in FIG. 2 at (a).
In order for the DVD player to reproduce a disk with good compatibility and high reliability, it is ideally necessary that the disk have the linking shown in FIG. 2 at (c). However, the linear speed on the track varies by the effect of the disk's eccentricity even if the disk rotates at a uniform speed. Thus, when data is recorded on the basis of a synchronizing signal obtained from the disk, a non-recorded gap portion 15 as shown in FIG. 2(b) or conversely an overlap portion 16 of both data is produced as shown in FIG. 2(d).
In case the write-once recording medium such as DVD-R, when recorded as in FIG. 2(d), overlap portion 16 destroys recorded data so that capacity of error correction according to ECC (Error Correcting Code) becomes decrease. Extension of the interval of the overlap portion 16 will also affect the servo control. When we try to reduce the overlap 16 to the minimum not to affect the servo control in order that the error correction can be made according to ECC, the non-recorded gap 15 contrarily becomes easy to occur.
The originally recorded data of the overlap 16 of data, when tried to record on the write-once recording medium like DVD-R, is destroyed together with the overwritten data. In a prior art considering this problem as disclosed in JP-A-9-270171, the ECC block including the linking portion is skipped over as dummy data not to be read or dummy data is inserted only in the vicinity of the linking portion to reduce the lack of information to the minimum. Here, the dummy data indicates meaningless data different from meaningful data such as video data and management information.
In addition, when the non-recorded gap 15 is produced between data and data, both the original data and the added data are not destroyed, but servo control cannot be activated by the non-recorded portion so that the recorded information cannot be properly read out because the playback-only DVD player employs the DPD (Differential Phase Detection)-type servo control that uses recorded marks.
In another prior art considering this problem as disclosed in JP-A-11-25459, the start end portion of the data to be additionally written continuous to the closing end of the previously recorded data is overlapped thereon so that the non-recorded gap cannot be produced when the DVD player reproduces a recordable type recording medium.